1. Field of the Invention
The present invention relates generally to a Bluetooth™ unit, and in particular, to a Bluetooth™ unit that is also equipped to receive mobile communication service.
2. Description of the Related Art
Bluetooth™ is a global de facto standard for short range wireless connectivity between mobile devices such as portable PCs and mobile phones. Based on a low-cost, short-range radio link, Bluetooth™ cuts the cord otherwise necessary for digital devices for short range data transfer. For example, a Bluetooth™ equipped mobile phone and a Bluetooth™ equipped laptop can establish a wireless connection Bluetooth™ and is likely to become the standard wireless communication protocol for short range, low power communication between PDAs (Personal Digital Assistants), desktops, facsimiles, keyboards, joysticks and a whole range of other digital devices.
As shown in FIG. 1, a Bluetooth™ system supports a point-to-point or point-to-multipoint connection. A set of devices sharing a channel will typically also share capacity. This device set is called a piconet. The piconet is defined as a small ad hoc network created when two or more Bluetooth™-compatible devices recognize and communicate with each other. Up to seven Bluetooth™ units can join a piconet, with one unit acting as a master and the others acting as slaves. The master manages the piconet including generation of a frequency hopping pattern.
When no connection is established between Bluetooth™ units, this is called a standby state. In the standby state, each Bluetooth™ unit receives a new message every 1.28 sec. Upon receipt of a connection request, a Bluetooth™ unit becomes a master and then starts to recognize other Bluetooth™ units. Bluetooth™ units are then assigned an 8-bit park address. Slave Bluetooth™ units communicate with the master once they receive a 3-bit active address, forming a piconet. Among the eight addresses that are representable with three bits, one is used as a broadcast address and the other addresses will be assigned to the seven slave Bluetooth™ units that can join a piconet. The Bluetooth™ units in the active state can be divided into three modes: active mode, hold mode, and sniff mode. Although Bluetooth™ units in the hold mode and the sniff mode participate in forming the piconet, they have no influence on the total traffic and consume less power than units in the active mode. The master transmits an inquiry including a link key at every 625 μs interval and synchronizes with its slaves within two seconds. The slaves are then assigned 3-bit active addresses and, after receiving a page message from the master, are synchronized with the master using the hopping pattern determined by the master. An authentication process follows. An encryption key for authentication is formed by XOR-gating a random number generated by the master with the Medium Access Control (MAC) address of a slave. After the authentication, a data transmission state is entered.
The master controls all traffic on a channel. A plurality of independent and asynchronous piconets form a scatternet. Users of each piconet have a 1-MHz hop channel in the scatter net. Because the 1-MHz channel is not shared with other piconet units, the total throughput increases as piconets are added. Scatternets are formed by connecting piconets, wherein a Bluetooth™ unit can act as a slave in one piconet and as a master in another piconet.
While there exists message transmission technology for information sharing between master and slave units using Bluetooth™ communication system, the prior art does not allow sharing of information on a Bluetooth system when that information is received in a wireless communication format, typically by a Bluetooth™-equipped cellular phone. That is, a Bluetooth™ unit receiving a message from a mobile communication service (e.g., an SMS message) cannot retransmit that message to other Bluetooth™ units. In other words, although digital information can be shared between Bluetooth™ units, the subject invention provides a means of sharing a message received from a mobile communication service with devices connected by a Bluetooth™ system.